Laser based scanners have long been used for detecting information about objects. One common use of such laser scanners is for detecting three-dimensional information about an object being imaged. The capability of deflecting laser or light beams is of great economic importance in the fields of optical switching, all-optical networking or photonic switching. Deflecting light beams is often performed by a servo-driven galvanometer or mirror scanner. Scanning can also be carried out by using crossed acoustic waves in a surface acoustic wave device.
Mirror-based devices are often designed for high frequency response. This may necessitate a light weight design. This in turn may compromise the structural integrity of the device.
Surface acoustic wave devices are often of poor directional and attenuation properties.
Movable mirrors may also be positioned by analog or by digital techniques. The Texas Instruments digital mirror, and the new Bell Labs analog mirror deflector (http://www.lucent.com/livelink/127844_Brochure.pdf) are MEMS devices using movable mirrors. TI is a digitally controlled device, and Lucent uses analog control. Analog control is difficult to achieve in the Lucent switch with desired accuracy because of the nonlinearities of the cantilever system used The electrostatic actuation in a cantilever is nonlinear in force. The force between capacitor plates and this nonlinearity may render the control complex.